This invention relates to a catheter. More particularly, this invention relates to a catheter with a wire guide for receiving a guidewire for aiding in a catheterization process. This invention also relates to a catheterization assembly.
Balloon angioplasty catheters and most atherectomy instruments, such as cutting and scraping devices, require over-the-wire guide systems. The guidewire directs the distal, working end of the catheter around bends in a blood vessel and serves in positioning the catheter tip into or through an appropriate area of an occlusion. This guidewire method minimizes injury, dissection and perforation of the blood vessel wall.
In currently used guidewire systems, there is usually both an extra lumen in the catheter through which the guidewire slides, stiffening the catheter, as well as a bend in the guidewire as it enters the catheter body, increasing the sliding friction between the catheter and the guidewire. See, for example, U.S. Pat. No. 5,061,273 to Yock and U.S. Pat. No. 4,748,982 to Horzewski et al.
In conventional guided catheters, the guidewire enters the catheter through the sidewall and at the distal end of the catheter. In such an assembly, the bending of the guidewire at the entrance hole, as the catheter slides over the wire, has a tendency to pull the end of the guidewire out of an artery or vascular side branch. This pulling occurs frequently, for example, where a guidewire cannot be placed too deeply into a coronary artery.
A further disadvantage of this conventional catheter guiding technique, if there is no separate lumen, is that a hole formed in the catheter sidewall for the passage of the guidewire leaks liquid from the side of the catheter rather than from the distal end where the liquid may be required for X-ray imaging, bathing the catheter tip, or clearing the field of blood. It is also possible that if the guidewire enters the catheter near its distal end, the bent guidewire will tend to tilt the catheter tip so that its aim is off center.
Particularly in coronary work and peripheral procedures below the knee, it would be highly desirable to minimize the number of lumens in the catheter, thereby increasing the flexibility of the catheter. In addition, particularly in such procedures, it would be advantageous to avoid sharp bends in the guidewire, thereby reducing friction between the guidewire and the catheter when the catheter is being moved to an occulsion. It would also be desirable to maintain the guidewire in a coaxial relationship with respect to the blood vessel right up to a blood clot.